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What’s in your water? (part three)

In this installment on water, I’m going to report on my findings from my water treatment experiments so far.

As a disclaimer I am not a scientist, nor should my methodology be viewed from that perspective. I am a home hobbyist, using the somewhat unsophisticated and mostly uncalibrated testing material available to the aquarium hobby. At best my results should be viewed with skepticism and are only presented here to give you an idea of what is working for me. Time will be the ultimate test, as I start to put this “vitamin C water” into use I will no doubt have issues that arise, and I will do my best to update as I continue to learn. You will notice I have primarily focused on chloramine and ammonia in these tests, as they are the two most concerning things in my water as far as fishkeeping goes. Another area of some concern and controversy is fluoride, but I’ve chosen not to focus on that because the levels in my area are very low – around 1ppm. At these levels the effect on plants and livestock should be fairly minimal.

Before I get on with the results, I want to do a quick review of the nitrogen cycle as it applies to fish tanks, so that the test results will mean more to you as you look them over. A fish in an aquarium lives in a closed system, meaning everything that is added to a tank stays in the tank until removed by the fishkeeper. This means that the smaller the tank, the smaller the change required to throw the system’s balance out of whack. This is why the “betta fish bowls” that are still being sold at pet stores everywhere are such a horrible idea. They are so small that the slightest bit of contaminant that is introduced will probably kill the fish. For this reason, I try to keep fish in tanks no smaller than 10 gallons.

As you feed your fish, you are adding material to the closed system, meaning it’s not truly “closed” after all – there’s now an “input”. The fish then eat the food they need, and any extra sinks to the bottom and begins to decompose. After the fish digests the food, they must excrete their waste product just like every other organism, so this also sinks to the bottom of the tank and begins to decompose. The primary chemical result of these things breaking down is that ammonia is released into the tank water and substrate (e.g. gravel). Ammonia, it turns out, is toxic to life in amounts as small as 0.5ppm (parts per million) and at that level will kill fish within a day. So how are those fish in the tanks at the zoo alive? That’s where the nitrogen cycle, or biological filtration, comes in. In a natural setting, like a lake or pond, the dilution effect is huge, but the water is also teeming with bacterial life that live and thrive by eating ammonia. These are called nitrifying bacteria, and they are the next step in the nitrogen cycle. When established in sufficient numbers they consume some oxygen and a huge amount of ammonia – easily up to 5ppm in a short period of time in an established tank, which is more than a safe load of fish in an aquarium will produce. But we’re not done yet, these organisms which eat the ammonia then excrete a waste product called nitrite. This by-product is also toxic and dangerous for fish at any level, as even small amounts under 0.5ppm can damage their internal organs. Levels over 10ppm are considered instantly fatal. So once again we need another form of nitrifying bacteria to come along and eat the nitrite – and that’s exactly what happens. Once the second round of good bacteria are established, the nitrites are consumed as quickly as they are produced, and thus we get their waste product – nitrate.

Aha! Something any gardener will recognize as an absolutely essential macronutrient (aka fertilizer) for growing healthy plants! And also the primary reason aquaponics is so interesting – because with an established system you are working with something almost completely self contained. The only input is fish food and top-off water, and the outputs are all edible or compostable! Nitrate, it turns out, is not only essential for the growth of plants, but is also only toxic to fish at levels over 50ppm. This gives us a much greater margin to work with, and a great deal of nutrition to feed our plants!

In a typical aquarium without a huge mass of green plants to soak up the nitrates over time, the fishkeeper is required to do a water change – remove a portion (10%-50%) of the nitrate-rich water from the system and replace it with freshly treated water from their water source. For lightly planted or unplanted tanks over 10 gallons, this needs to be done as frequently as once per week. That’s a lot of water (and fertilizer) down the drain! But once you start working with a tank stocked full of green plants to soak up the nutrients, all of a sudden there are fewer water changes to do, and more time to work on more interesting projects – like growing food!

So… let’s get to the results.

First, I am happy to report that, at least for my area, my tap water test results did not stray far from what the city I live in claims on their annual report. The water coming out of my tap is safe to drink as it is, at least by their guidelines, and any additional filtering and treatment I do will only make it safer for my family, my plants, and my fish. Let’s remember that the levels of contamination we’re talking about are incredibly small… we’re talking in parts per million, not in percentages. Also for us humans, our digestive systems are fully capable of processing such a small amount of chloramine so that by the time the water is in our soft tissues no detectable levels are present. For fish, however, who live in water 100% of the time, the chloramine is incredibly toxic – it passes right through their gills with every gasp for breath, coming into direct contact with their soft tissues.

For my tests, I started with two 5 gallon buckets of water straight out of the tap at approximately room temperature. Into bucket #1 I mixed the standard amount of commercial water conditioner I always use when filling my fish tanks. Bucket #2 was left alone for the time being, so that I could test the tap water. I then took samples from each bucket for chlorine.

On the left is bucket #1 (treated) and on the right is bucket #2 (untreated tap water). This confirmed that the water conditioner was doing its job and removing all traces of chlorine and chloramine from the water. It also confirmed that I had about 4ppm of total chlorine with maybe 0.5ppm of free chlorine present at the tap. To determine how much chloramine is present we simply subtract the free chlorine value from the total chlorine value for roughly 3.5ppm of chloramines in my tap water. So, the water conditioner is great! But…

I’ll keep using this stuff on my fish tanks for now for two reasons. First, it not only deals with the chlorine, but also the residual ammonia from the chloramines. Second, I don’t yet know what the long-term effect of my alternative solution, ascorbic acid, will be on the aquarium ecosystem and its inhabitants. I am eager to get an alternative figured out soon, so that I can start feeding my plants the wastewater from my fish tanks.

Next, I thought I’d check out what my standard pitcher-type charcoal filter was doing about the chlorine in my water. I took about 1.5 quarts of water from the untreated tap water sample (bucket #2), and let it run through the drinking water filter. It took about 7 minutes to filter this small quantity in a fairly new filter (changed maybe 2 weeks ago.)

From left to right we have treated water (bucket #1), filtered water (bucket #2 post-filter), and unfiltered water (bucket #2). It’s clear from this that even a modest pitcher filter is doing something, as I see only about 1 or at most 2ppm in total chlorine present after the tap water has gone through the filter – that’s up to 75% of total chlorine filtered out of the tap, not bad! Given the rate of filtration and the fact that there is still chlorine in the water, however, means this is not a viable option for treating tap water for aquarium use.

So here goes the Vitamin C!

To deal with the small levels of chloramines coming out of my tap, I need to add just under 400mg of ascorbic acid to each 5 gallon bucket I will be treating. You can find ascorbic acid in 500mg capsules that would make dosing a 5 gallon bucket a no-brainer, keeping in mind that every little bit of acid you add will shift your pH down proportionately. My local co-op had an 8oz. container of ascorbic acid powder rather than the capsules, so I opted for that. It was about $15, but at the correct dosing amount, I’m able to treat over 550 5gal buckets with one container. I’m using a small fish food scoop and adding 3 of those, which should give me 350-400mg total dosing per bucket. For reference, 1/8 teaspoon is approximately 500mg of ascorbic acid powder, depending on the grain size.

The ascorbic acid reacts with the chloramines in water, releasing three by-products: free chlorine, dehydroascorbic acid (a form of vitamin C beneficial to living organisms), and ammonia. So we’re not there yet! The good thing about the conversion to free chlorine is that this compound is now able to evaporate, or out-gas, from the water. This happens fairly quickly, and is why we used to leave our buckets of water out overnight to age before adding them to our fish tanks. So we’ve replaced the stable chloramine with an unstable chlorine, which will evaporate out of the water… we’re getting closer – assuming this works!

To speed things up, after adding the ascorbic acid (roughly 375mg) to a nearly full 5 gallon bucket, I drop an airstone attached to an air pump into the bucket. This aerates the water and keeps it moving so that all the chlorine will out-gas – it’s not necessary but ensures more reliable results.

I head off to work, and 9 hours later am excited to see the results!

Great success! The test strip on the bottom is from the Vitamin C treated water, and shows no residual chlorine after 9 hours of bubbling away! You can see the other test strips from earlier above, now dried out and less colorful. I will be testing this further to see exactly how long I have to leave the water to out-gas before using it.

What about pH? Did the acid I added to the bucket bring down the pH a dangerous amount? Well, here’s the pH level before ascorbic acid was added…

Hard to say for sure, but I’d guess that’s a reading around 8.4 – which is fairly alkaline. Next is after the test cycle was run…

That looks like about an 8.0 – so we’ve definitely dropped some pH, but as you can see from the “low range” test it has certainly stayed above 7.6 regardless. As I mentioned earlier, it’s a benefit that my water started out fairly high in pH, so this small swing should not adversely effect the viability of the water for aquarium use.

I also tested for Phosphates, Ammonia, Nitrites, and Nitrates, just to be thorough. Phosphates and Nitrites were, as expected, at zero. Nitrates actually surprised me by coming in at just over 10ppm – I will have to monitor my tap water for a little while just to see if this drops back down to expected levels. At any rate it is not enough to pose a problem even for fish, and should be a benefit for plants. Ammonia is the only real area of concern, as there are detectable levels in the water now up to 2ppm. This means that I would not want to take a fish out of its tank and drop it in a bucket of water treated with ascorbic acid, but the biological filter (or nitrogen cycle) in an established tank should be able to deal with this level pretty quickly. Where did this ammonia come from? Remember I mentioned that chloramines are chlorine bound with ammonia? Well, we released the chlorine, and that left residual ammonia behind.

In conclusion, it looks as though Vitamin C might actually be a viable option for treating water in absence of aggressive whole-house filters, in order to remove chloramines which are otherwise difficult to get rid of. The quantity needed is very small and inexpensive on a per-use basis, and this will allow us to raise fish and water our plants without destroying the necessary nitrifying bacteria which live in our soil and our fish tanks.

If you are interested in learning more about what is in your water, I encourage you first to search the internet for “water quality report” along with your city/municipality name, as most of these are available online. If you want to do your own tests to check out what is coming out of your tap, there are some affordable options out there without having to mail a sample away to a lab. First, your local fish store will most likely sell a test kit for under $30 that will test for ammonia, nitrite, nitrate, and pH – sometimes even hardness (GH and KH). These are titration kits, which means that you will be handling some dangerous chemicals so I urge you to use caution, keep them out of the hands of children, and wash up well after handling. The funny thing is that I have yet to find an aquarium store that sells chlorine tests – for this you will need to do some digging online or find a pool supply store that will sell you a DPD test kit for both free and total chlorine. I wound up finding a test kit from an online chemical company that cost me about $18 for 50 tests – the nice thing about these as you saw is that they are litmus-style strips which means I don’t have to handle or store any toxic chemicals. Some pool supply companies will sell test kits that include a battery of tests like the ones sold at fish stores, so shop around for the best deal in your area. There are also “well water test kits” available online that most likely work the same way.

That’s about it for my thoughts on water for now. Hopefully you enjoyed learning along with me and have started to think about the importance of water quality as it relates to supporting living ecosystems – for whether we are talking about gardening, fishkeeping, farming, or simply the water we drink, it is one of the most fundamental building blocks of health and life that there is!

I will continue to update occasionally on how the ascorbic acid treatment does with the fish tanks over the long term, as I continue to learn and work towards an aquaponic setup. But for the near future I am going to be planning out my summer garden(s) and working to revamp my indoor greens growing operation, so look for more updates from the homestead soon!

The community garden plot we applied for is usually a lottery, so we won’t know for a few weeks. If we don’t get it, I may just ramp up my food production on our balcony – there’s about 22′ of railing that gets pretty good sun.

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